In a surveillance system, because the image data of the surveillance system occupies much storage capacity of the surveillance system, a motion object detection technology is developed for solving this problem. The motion object detection technology is be used to detect a foreground object in a surveillance image. The surveillance system adopting the motion object detection technology would not store surveillance image or send out warning messages until the foreground object is detected in the surveillance image.
In a conventional motion detection technology, a present image caught by a camera of the surveillance system is compared with a pre-build background model to get pixels having greater pixel value difference. Then, the pixels are converted to foreground objects. Thus, the surveillance system can determine when to store surveillance image or send out warning messages by estimate the state of the foreground objects.
However, the conventional motion detection technology cannot provide the background model in accordance with the change of the brightness of a surveillance area. Therefore, when the brightness of the surveillance area changes, the surveillance system cannot determine when to store surveillance image or send out warning messages.